package unit13;

import java.util.BitSet;

public class Sieve {
	public static void main(String[] args) {
		int n=200000;
		long start=System.currentTimeMillis();
		BitSet b=new BitSet(n+1);
		int count=0;
		int i;
		for(i=2;i<=n;i++){
			b.set(i);
		}
		i=2;
		while(i*i<=n){
			if(b.get(i)){
				count++;
				int k=2*1;
				while(k<=n){
					b.clear();
					k+=i;
				}
			}
			i++;
		}
		while(i<=n){
			if(b.get(i))
				count++;
			i++;
		}
		long end=System.currentTimeMillis();
		System.out.println(count+"primes");
		System.out.println((end-start)+"milliseconds");
	}
}
